Problem: What do the following two equations represent? $-x+y = 5$ $-2x+2y = 10$
Explanation: Putting the first equation in $y = mx + b$ form gives: $-x+y = 5$ $y = x+5$ Putting the second equation in $y = mx + b$ form gives: $-2x+2y = 10$ $2y = 2x+10$ $y = 1x + 5$ The above equations turn into the same equation, so they represent equal lines.